The present invention relates to a scene change detector for video data.
In most video applications, it is difficult for viewers to navigate through video content in an intuitive manner. A viewer may desire to browse through video content by fast-forwarding or rewinding through it. However, most video data is indexed by a time scale or a frame counter. Because viewers typically do not think in terms of elapsed time or elapsed frames, such indices are not helpful to permit a viewer to quickly identify and select desired subject matter.
Lay users of conventional domestic videocassette recorders may be familiar with this phenomenon when they desire to watch portions of a favorite movie. Often, to reach a desired portion of a movie, it is necessary to fast-forward or rewind the cassette for an arbitrary period of time then play the cassette to determine at what point in the plot the cassette has reached. The xe2x80x9cfast-forward, then playxe2x80x9d operation is repeated in essentially a hit-or-miss fashion until the viewer has reached the desired portion of the movie. Of course, many conventional video cassette recorders display a running count of elapsed time or elapsed frames while a cassette is fast forwarding. Nevertheless, the xe2x80x9cfast-forward, then playxe2x80x9d operation is used because viewers do not intuitively correlate elapsed time or frames to video content.
Certain other video applications, for example the later-generation digital video discs and the MPEG-4 video-coding standard, may permit video content publishers to provide semantic information to accompany the video data. Such semantic information, conceivably, could support an index to the information content within the video data. However, in such instances, viewers would be able to use such an index only if the video publisher deigned to create one. Further, particularly in the MPEG-4 example, such semantic information consumes precious bandwidth that the coding standard was designed to conserve.
Accordingly, there is a need in the art for a video application that permits viewers to browse and access video data in an intuitive manner. Further, there is a need for such an application that generates an index to the video information based upon the content of the video information and without consuming the communication bandwidth of the video data signal itself.
Embodiments of the present invention provide a method of building an index of a stream of video data, in which scene changes are detected from the stream of video data, reference markers associated with the video data are capture for those portions of the video data for which the scene changes were detected and the reference markers are stored.